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Updated: Oct 10, 2025
Author Spotlight: Integrating Alveolar-Capillary Reserve Measurements in Exercise Adaptation and Therapeutic Strategies
Published on: February 2, 2024
Diurnal variation in DLCO and non-standardized study procedures may cause a false positive safety signal in clinical
Krishna Tulasi Kirla1, Szilárd Nemes2, Joanne Betts3
1Patient Safety, Respiratory & Immunology, Chief Medical Office, R&D, AstraZeneca, Gothenburg, Sweden.
Abstract:
Diffusing capacity for carbon monoxide (DLCO) was measured in a phase I single ascending dose study after inhalation of AZD8154 or placebo in healthy participants at baseline (DLCOBaseline) and follow-up (DLCOFollow-up) 6 days after dosing. Initially, DLCOFollow-up timepoint was 2 h earlier than the DLCOBaseline timepoint and clinically significant decreases in DLCOFollow-up (absolute change up to 19% from baseline and DLCO%predicted values less than 70) were observed then. The observed reduction in DLCOFollow-up was confirmed as a false positive finding after alignment of DLCO timings. As a consequence, when DLCO is used in clinical studies, measurements should be strictly standardized in relation to time of the day.
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